Jeep Wrangler Maintenance and Repair Questions (1997 - 2006)

mjm1965 · July 2009

At various times while driving in on the highway my jeep will start to buck , run rough and backfire. I pull over to the side of the road and let it idle or turn the engine off for a ew minutes then start it up and it runs fine for a while.

The only time this happens is when I am on the highway, in 5th gear and not shifting.

If I am driving, shifting and changing speeds it does not happen.

Any ideas as to why this happens.

Thanks

erickpl · July 2009

Any codes being thrown or the check engine light coming on?

-Paul

mjm1965 · July 2009

Sometimes the check engine light comes on.

No codes.

mac24 · July 2009

Sometimes the check engine light comes on. No codes.

An illumination of the MIL is a cause for concern. It means that there's a problem that could possibly affect driveability.

When the light comes on the PCM generates a code so that you can see what caused the light to come on. You do have codes, or at least one.

erickpl · July 2009

Run by AutoZone or a place like that and they should be able to plug into the OBDII port and get the code it is generating.

I'd place my money on a throttle sensor.

-Paul

mjm1965 · July 2009

Thanks.

We had talked about it being the throttle sensor.

This was the first time its happened in a while. I am going to check the code and dig into it this weekend.

Mike

erickpl · July 2009

TPS is an easy swap once you know where it is.

-Paul

jeepmaniac13 · July 2009

I have changed a lot of things in this jeep I changed the water pump the radiator the computer the map sensor I have regular 30x9.50 15 tires I have put octane booster injector cleaner and no mechanic knows what is wrong with my car and i literally get 80 miles on a one tank of gassss... hellp .. black smoke comes out of it when i rev the engine and it takes me forever to get to the speed of the highway :lemon:

mac24 · July 2009

..................................i literally get 80 miles on a one tank of gassss... hellp .. black smoke comes out of it when i rev the engine and it takes me forever to get to the speed of the highway

While many things could cause this, the bottom line is that the poor mpg and black smoke indicate it's running a very rich fuel/air mixture.
It could be as simple as a blocked air filter, or as complex as several bad sensors in combination with fuel system issues.

Take it to a competent professional shop.

jeepmaniac13 · July 2009

ive taken it to a real mechanic and it comes up as a sensor o2 but i changed one of them and cleaned the other one

roadburner · July 2009

You need to find a real mechanic- not merely a part swapper.

erickpl · July 2009

Mac's suggestion about the rich mixture is probably the first thing to look at. You may also want to ensure you've got good plugs/wires electircal distribution to each cylinder. When was the last time the differential and transmission fluids were changed?

My 2.5 is no fuel sipper, but get more than 7 mpg.

Even with armor and 33" tires.

-Paul

mac24 · July 2009

it comes up as a sensor o2 but i changed one of them and cleaned the other one

An O2 sensor can't be cleaned, just further damaged. Was it the one before or after the cat?

elscarecrow · July 2009

Since you guys are talking about the 2.5, I have the very same problem with the bad mixture, but my question is I get frustrated with the slow speed after putting the pedal to the floor when going up miniature hills and it wont go any faster. Traffic catches up to me and began to tailgate. I have 31 tires. Can the speed be enhanced? One person suggested changing the differential gears. Any suggestions?

captjax · July 2009

Thanks for all your help with the last issue with my AC. The problem has since been resolved.

That said, I've got a new issue (ugh...) I'm getting a knock in the front axles when I go around most turns. For instance, if I turn left, it'll knock. When I straighten out or turn right, it'll knock. Nothing loud, just a noticeable knock. It also might be affecting performance at speed. I'm kind of getting a wobble, but I can't tell if it's the wind (it's been real windy here since this started).

CV joints?

erickpl · July 2009

Even with my 30's, the 4.10 gearing in my 2.5 hurt. Stock wheels on the SE are 29's. When I went to 33's, I regeared the diffs to 4.88. Still not a barn burner, but I can carry 65-75 up inclines MUCH better, though I'll still downshift to 4th to keep the engine in the power band if necessary.

Other things you can do are to make sure your water pump and other pulleys rotate freely so as to not create drag. Other options include an electric fan that doesn't rely on engine rotation to turn. If you want to dive into the engine you can do:

1. Upgraded Cam kit.
2. Heavier inertia ring
3. Turbo charge it.

I haven't tried 1-3 above, but what I've read on various jeep sites. I make no claim as to how much you gain from them.

I've also found with the 2.5, that mashing the floor to the pedal don't do squat! When I find myself doing that, I pull up on the pedal a bit until the 'pinging' in the engine stops. Same speed, just less gas being dumped in there. Found I'm going just as fast but with better mileage.

And here's my TJ today, to prove I'm on 33's.

-Paul

mac24 · July 2009

I'm getting a knock in the front axles when I go around most turns...............CV joints?

You don't have CV joints, but you do have UJs on the front half shafts and it could quite possibly be those.

mac24 · July 2009

I have 31 tires. Can the speed be enhanced? One person suggested changing the differential gears.

Yes, but it will have more of an influence on acceleration than top speed.
However, you need to fix the mixture issue first. Not much point in making other changes until the engine is producing its best.

k_oner · July 2009

i have noticed on many jeep sites that I am having some of the same trouble as most of the other 97 wrangler owners . started running rough then lack of power ! did a tune up cap and rotor plugs and plug wires and even the coil checked the valves and replaced the valve cover gasket . replaced the tb gasket and also the intake/exaust gasket. have been reading that a few people have went and did a valve job and cleaned the combustion chamber checked the cat for restriction and even went and changed the whole distributor . mine has over 160k on it used to run like a raped ape and now theres a misfire in one or more cylinders
are the injectors leaking, cam shaft sensor bad. fuel pressure regulator clogged need help b4 i decide to let it go

jdgolf · July 2009

I was covering my jeep when I noticed a hose on the ground coming from my jeep. I followed it up to the top of the front differential. I have no idea where it goes to? Could someone please help me? Thanks in advance.

Bill

roadburner · July 2009

It's the breather hose. It mounts in a clip on one side of the radiator- the driver's side I believe.

erickpl · July 2009

Yup, just behind the radiator overflow. Just ziptie it up there and drive on.

-Paul

jdgolf · July 2009

I have a 2000 Jeep Wrangler and every once in a while when I start it the blinkers, windshield wipers and radio won't work but the hazard lights and headlights work. Most of the time they work fine. I am clueless. Please help and thanks to the genius that can figure this out.

erickpl · July 2009

Had a similar issue on a BMW I had purchased. Problem was in the cluster control unit (not sure if this is the PCM or not). It ALMOST sounds like you have a loose ground somewhere. The wiper and blinkers are in the same assembly, so if you can trace that down, I wouldn't be surprised if you found a common ground point with the radio. There are a few known grounds on the TJ. One is up under the driver footwell against the side. Check there for any loose wires screwed to the tub. I'm sure Mac could point out other locations, but your symptoms being occasional has me thinking loose/bad ground.

But I am NOT an electrical expert.

-Paul

cjw42 · July 2009

I have a 04 jeep wrangler sport 6cyl. The engine runs rough and I get a engine code 0303 miss fire # 3 cyl. I ruled out the injector is there any way to check the ignition coil pack.

Thank you for your help.
Cary

crzntj · July 2009

Hello, I have a 97 Wrangler TJ, 4.0L, manual tranny.
Several months ago, my Jeep sounded like it was tumbling rocks, thought it could be Catalytic Converter, never had it checked out as it finally stopped after a few weeks or so. However, now I have a new problem that just started, after the engine is warmed up, it will begin to sputter randomly at cruising speed, the tachometer will sometimes drop to zero, and check engine light blinks on for a second, then it will run fine for a little while longer. Now today, it has gotten so that it actually stalled on me twice for a split second while down shifting to 2nd to turn a corner. When I push clutch in and rev engine without turning ignition, it will come right back to life again....I believe it did pop once. Then it did it again right down the street.

Do you think this could be the Catalytic converter finally dieing and causing this, or do you think I may have an entirely different issue? Perhaps, ignition on the blink? We have not checked for a code as of yet with an OBD. Why? Because my husband is tired of working on my Jeep!

So, I've resorted to asking some experts here on this site so that I have something intelligent to ask him to try next!

We've just replaced all plugs, cap, rotor and wires just yesterday to see if that would help. All of the above looked in good shape, not really needing to be replaced. No loose or frayed wires anywhere, battery and cables all good!

Quick side note; I have 37 inch tires, was having issues with ABS. Disabling the ABS system shouldn't have anything to do with this stalling issue correct?

Thank you in advance for any suggestions and help anyone can give. :shades:

maryp001 · July 2009

I have a 1997 jeep wrangler. While driving today my battery guage shot to the 19 and the check guage light came on. Any idea what this could be?

maryp001 · July 2009

There is a recall on catalytic converter on 97 wrangler. I just had mine replaced, I was having the same problem.

maryp001 · July 2009

Hi. My 1997 Jeep Wrangler is having the same problem. Took it to 2 different mechanics (jeep dealership) and they can't figure it out. Did you ever figure out what it was? I love my jeep (my second) but it's been really having so many issues this year. wow.

go_topless · July 2009

MY AC ONLY WORKS IN THE 4TH POSITION. CAN ANYONE HELP ME OUT.
05 JEEP WRANGLER

maryp001 · July 2009

Hi. I have had a bunch of problems with my 1997 Wrangler lately.

First, it would crank but not stay running unless I kept my foot on the gas. At the same time while driving, the battery gauge would shoot up to 19v and check gauge light would come on.

The only trouble code from the PCM was the o2 sensor. Changed that along with a recall on the catilitic converter. (Alternater/regulater was fine). Changed the battery as well.

Now it runs fine but battery gauge still shooting up to 19v every now and again.
I have had it to 2 different Mechanics and they can't make it shoot up and there are no trouble codes.

I have heard of a couple of people having the same issue although they sound unrelated, but have not heard out come.

Any ideas?

rinski14 · July 2009

Hi! This is my first post and I hope you can help me as much as you've helped everyone else!

I just made an appointment with a local mechanic to have a diagnostic done because the engine light just came on. Before I hear what he has to say, I wanted to get your opinion.

For the past couple of months when I start my 2003 wrangler sport automatic v6 it makes this banging noise for a few seconds before it evens out.....then it drives fine. I didn't know if this is some type of misfire triggering the engine light.

The only other problem I've had recently that might have contributed to the engine light is my battery dying due to leaving my sirius radio on (old battery....needs to be replaced). When i jumped it a couple days ago i had to leave my foot on the gas to keep it from stalling. I finally let it stall out and started it right back up and it was fine.

Also, the Jeep dealer (they went out of business and i'm not gonna shed a tear because the mechanics were pushy and never did anything right!) said it was necessary to get a radiator flush for maintenance. At almost $300.00 I wanted to make sure I needed it before i did it. My jeep has 69,000 miles.

Help! I'm not mechanically inclined so some guidence would be great.

mgarvie · July 2009

AC blower motor resistor is bad

rinski14 · July 2009

I have the same problem with both my AC and my heat in my 03.

crzntj · July 2009

Thank you for the info. I've tried finding info for a Cat recall online, can't find anything so far. I do believe you though, I've heard a few people mention it. However, I did pass smog, so not sure if anything is wrong with Cat or not...would still like to have replaced if recalled.

We did finally solve the issue with the Sputters and Stalls....for anyone else wondering, it ended up being a loose wire on the Crank Shaft Positioning Sensor. Fixed that and it runs like a champ once again!

I had a 93 Cherokee automatic, a few years ago back that would suddenly stall and not restart for about 10 minutes. Chrysler couldn't tell me why this was happening, even though my life was in serious danger, as it would randomly stall even in the middle of the freeway!! One lady was killed in her Cherokee on the freeway due to a stall like this.

This serious incident ended up being the Crank Shaft Positioning Sensor as well...Only a $100.00 part from the dealer!! Not worth one's life...very easy fix! For anyone else having similar problems...check it out.

For some reason, Neither one of my vehicles would not show a code for this problem on the OBDII. But once replaced, they both ran perfect!

kufu · July 2009

I have 1999 Jeep Wrangler TJ, 2,5L 4 cyl. Two hoses are connected to the top of the valve cover. One of them has oil on itself on the bottom where hose go to the engine. Same rubber hose has plastic one inside. What is the name of that hose?
So far not much drops of oil on the floor in my garage, but......
Thanks,

kufu · August 2009

Hi,
I just want to share this: JCWhitney sell Black 3" Diametar Side Step Rails a pair
for total 143.98. Price is to good to pass it up.

kitroll · August 2009

Hi.. I have a 2003 jeep wrangler and i love it except it jerks really hard sometimes and after i drive it for over an hour or so and come to a stop and then go to take off it hesitates likes it out of gas or something. I want to fix it but nobody knows whats wrong with it .I took it to a tranmission shop who charged me 300.00 to clean all of those little parts and peices in there that worked for about two months , I always have the oil changed when i am suppose to , add fuel injecting cleaning stuff when i fill up with gas , I know nothing about this stuff but even my honey and his friends can't figure it out . please if anyone knows how to make this go away please let me it is driving me nuts!! :confuse:

mac24 · August 2009

Both hoses are crancase vent hoses. Hose #1 sucks oil fumes from the crankcase via the valve cover and into the engine to be burned. The oil fumes are replaced by clean air from the air filter via hose #2. The direction of flow is shown by the red arrows.

mac24 · August 2009

I took it to a tranmission shop who charged me 300.00 to clean all of those little parts and peices in there that worked for about two months

It would appear that the problem is connected in some way with whatever the transmission shop worked on as they fixed it, if only for a couple of months.

Go back to them and check what was actually done in detail.

erickpl · August 2009

Are you sure it is a transmission issue? Have you run by any local auto part stores like Auto zone to see if it is throwing any codes?

Have you had your differentials (in the axles) and transfer case fluid changed any time recently?

Opening up the differentials may tell you if you have gear damage at the axle itself.

-Paul

kitroll · August 2009

i am so glad somebody responded thankyou last night i crawled under there and saw some wettness my honey has just said he will check the fluids but that wouldnt have anything to do with the hesitation after driving for long periods would.. sorry for all the stupid questions..

erickpl · August 2009

The wetness could be from humidity, condensation, or a leak. The hesitation sounds like the engine may be throwing some codes. That's why I suggest hitting up Autozone or a place to read any codes your OBDII is tracking.

-Paul

kitroll · August 2009

ok sorry so i didn't tell you this but the check engine light did come on about a month ago on my to get oil changed then had codes read there was one which was something like fuel air metering they reset it and about a week later giving gas to get on highway it came on again so i changed the thermostat which was bad it came out in 4 pieces i reset it by disc the battery went back to auto zone the code was gone.

erickpl · August 2009

To me, sounds like more of an issue with your engine vs your transmission.

-Paul

jdlj · August 2009

I have an 04 jeep wrangler unlimited 4.0 inline 6 cylinder, it has an airaid air filter, a throttle body lift, 33 inch tires, winch, warn bumpers around with tire carrier, a 2 inch body lift and a 2 inch suspension lift and I get between 16.5 - 17.5 mpg highway and around 15 city. I say all that to say that something doesnt seem right to me regarding your poor fuel mileage. I pulled a basstracker 17.5 foot boat to and all around Colorado and averaged 11 mpg.

erickpl · August 2009

With your 33 inch tires, did you regear the differentials? If not, your speedometer (and odometer will be off). So you may be getting decent mileage (but don't expect GREAT mileage with 33's) but just don't realize it.

There are a number of speedo gears available online. You need to check with the dealer for a gear that works with 33" tires and the gearing in your differential (likely 3.73).

-Paul

oonikki1015oo · August 2009

I have a 2002 JEEP TJ. For the past month every once in a while it has had problems starting. It would start but it was struggling to start. Just last night it died. I try to start it and you can hear something turning but not connecting. I think I just need a new starter but I'm not sure and I don't want to buy one if that's not the problem. Does anyone have ANY idea what it could be?

srtreat83 · August 2009

We have a 97 Jeep wrangler. Ok so in the offroad course park last weekend my husband and I went through some pretty deep water in which the little hill at the beginning kinda made the hood & front in dip into the water first. A few minutes later it started cutting out and died. It started back up and died as soon as we started to take off. Since then it will either not start at all or die after a few minutes of idling or die when you start to drive it. We have hair dryed the rotor and distributor cap ( not sure if that is the right name and hubby isnt here) and that seemed to help make it run longer. Whenever it doesn't start it turns over but doesnt start. No fuses are blown under the hood except the cig lighter. My husband is notorious for guessing at what is wrong and fixing 10 things that are perfectly fine before finding the real problem so I just thought I would try to see if anyone might know... Any ideas?

erickpl · August 2009

EXACT same thing happened to me. Check the Throttle Position Sensor behind the air intake at the top of the engine. Go to Autozone and have them read any codes. I'd be willing to bet the throttle position sensor is bad. It can be sensitive to water/mud.

It's a 53.00 part or so and 10 minutes in the parking lot changing it out.

As for the poster above you, check codes as well before doing anything. Your ODBII port should hold any codes as well, so before doing the part swap boogie, see if the Jeep is telling you anything.

-Paul

Jeep Wrangler Maintenance and Repair Questions (1997 - 2006)

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